Method and apparatus for wet spinning elastomeric polymers into a fused multifilament fiber



Dec. 15, 1964 T. v. PETERS, JR 3,161,706 METHOD AND APPARATUS FOR WETsmmmc ELASTOMERIC v POLYMERS INTO A FUSED MULTIFILAMENT FIBER FiledSept. 28, 1961 2 Sheets-Sheet l INVENTOR TIMOTHY V. PETERS, Jr.

m M, M

I Mm ATTORNEYS Dec. 15, 1964 1-. v. PETERS, JR 3,161,706

METHOD AND APPARATUS FOR WET SPINNING ELASTOMERIC POLYMERS INTO A FUSEDMULTIFILAMENT FIBER Filed Sept. 28. 1961 2 Sheets-Sheet 2 Emma-7'ATTORNEYS PM, M, 70127,-

United States Patent 1 WTHQD AND APPARATUF: FGR WET SEHNNTNG ELASTOMERICPQLYMERS INTG A FUSED MUL- TTFILAMENT FEBER Timothy V. Peters, in,Barrington, RL, assignor, by

mesne assignments, to Polythane Corporation, Rumford, RL, a corporationof Delaware Filed Sept. 23, 1961, Ser. No. 141,530 7 Qlairns. (Cl.264-103) This invention relates to a method and apparatus for the wetspinning of filaments from solutions of elastomeric polymers commonlyreferred to as polyurethanes.

Wet spinning of elastomeric polymer solutions involves the extrusion ofan elastomeric polymer solution through an orifice into a coagulatingbath. The filament is formed as the solvent difiuses out into thecoagulating bath. This diffusion is generally accompanied by thepenetration of the coagulating bath liquid into the filament.

The spinning of isocyanate modified dihydroxy elastomeric polymersolutions by the wet spinning process has not been particularlysuccessful. The filaments produced by this process have been weak andhave not possessed desirable properties. As a result of the failure ofthe wet spinning process to produce filaments having acceptableproperties, the isocyanate modified dihydroxy elastorneric polymersolutions have been transformed into filaments by a dry spinningprocess. The dry spinning process, however, is recognized as being quiteexpensive. It is also recognized that a wet spinning process, if itcould be used to produce filaments having acceptable properties, wouldbe much more desirable since it has numerous known advantages such ashigh productivity, low operating temperatures, large spinning orificesand so forth.

This invention involves a Wet spinning process for preparing isocyanatemodified dihydroxy elastomer fibers possessing the same excellentproperties as those fibers obtained from the more expensive dry spinningprocess.

The invention broadly involves the extrusion of an isocyanate modifieddihydroxy elastomeric polymer solution through suitable spinnerets orextrusion nozzles into a liquid coagulating bath to form filaments. Aplurality of the filaments are then gathered together and passed througha restricted area so that the pressure applied to them will press themtogether and consolidate them into a fused multi-filament fiber. Whilethe filaments are being pressed together they are in contact with thecoagulating fluid and are in a state of semi-plastic fiow. Themultifilament fiber is then subjected to a twisting action while it isin contact with the coagulating fluid and also in a state ofsemi-plastic flow. The twisting action which is imparted to themultifilament fiber is in the nature of a socalled false twist. Thistwisting action can be imparted to the multifilament fiber by causing itto roll over a smooth surface. The resulting multifilamen't fiber isthen dried and wound on a spindle ready for subsequent use in theformation of various garments or wearing apparel.

The solutions of isocyanate modified dihydroxy elastomeric polymers canbe prepared by various manners known in the art. The term elastomericpolymer has been used herein to describe solutions of isocyanate modificd dihydroxy compositions which are capable of being extruded into acoagulating bath to form filaments or other shaped objects. Theisocyanate modified compositions which can be extruded into acoagulating bath to form filaments have been referred to in the priorart in various manners such as prepolymers, semi-polymers and so forth.The term elastomeric polymer as used herein is intended to include allsuch extrudable isocyanate modified compositions.

Advantageously, the elastomeric polymers used according to thisinvention are prepared by reacting a difuncice tional hydroxylterminated polymer with a molar excess of an organic diisocyanate toproduce a low molecular weight isocyanate terminated prepolymer. Theprepolymer can then be reacted with a compound containing, in general,at least two active hydrogens in the presence of a solvent to form asolution containing the resultant elastomeric polymer.

Various difunctional hydroxyl-terminated polymers including polyetherglycols and polyester glycols can be used to form the prepolymersaccording to this invention. The molecular weight of the difunctionalhydroxyl-terminated polymers can advantageously be maintained aboveabout 700 and preferably between about 1,000 and 4,000. Difunctionalhydroxy terminated polymers having a molecular weight below about 700can also be used, but they generally do not result in end productshaving elasticity as advantageous as from those hydroxy polymers of bigor molecular weight. The value of such products produced with hydroxypolymers having a lower molecular weight will depend upon the end use ofthe product and the elasticity desired for that particular use.Generally, as the molecular weight of the hydroxy polymer is decreased,the elongation decreases and the modulus increases. The use of a polymerhaving a molecular weight in an excess of about 4,000 presentsconsiderable diificulties in the subsequent formation of the polymersolu tion and the transformation of such solutions into suitable anduseful products due to difiiculties in maintaining acceptablerheological properties in the resulting polymer solutions.

The high molecular weight polyester glycols which can be used accordingto this invention are those which contain terminal hydroxyl groups. Theesters can be prepared by various known methods by reacting diacids,diesters, or diacid halides with glycols. Suitable glycols which can beused to prepare the polyester glycols include polyalkylene glycols suchas methylene, ethylene, propylene and butylene glycols. Substitutedpolyalkylene glycols such as 2,2-dimethyl-1,3-propene diol as well asheterocyclic glycols such as cyclohexanone can also be used. Examples ofacids which can be used to prepare the polyester glycols includesuccinic, adipic, suberic, sebacic, terephthalic, as well as variousalkyl and halogen substituted derivatives of the acids. The polyesterglycol may for example be prepared by reacting the proper molar ratio ofthe acids or ester-forming derivatives of the acids with the glycols toproduce the high molecular weight polymers. The polyester glycolsprepared by reacting 2 mols of polyethylene glycol or polypropyleneglycol with 1 mol of adipic acid and then removing the glycol with heatand vacuum until a molecular weight of about 2,000 is reached canadvantageously be used to form prepolymers according to this invention.

The polyether glycols which can be used to form the prepolymersaccording to this invention are polyalkylene ether glycols havingterminal hydroxy groups. The polyalkylene ether glycols can be preparedin known manners and are generally prepared by the polymerization ofcyclic others such as alkylene oxides or from condensation of glycols.The polyalkylene ether glycols are represented by the formula HO(RO),,Hin which R is an alkylene radical and n is an integer sufficiently largeso that the polyalkylene glycol has a molecular weight in excess ofabout 700 and preferably in excess of about 1,000. The polyalkyleneglycols can be prepared by copolymerizing mixtures of differen talkyleneoxides or glycols. Examples of polyalkylene ether glycols which can beused in this invention include polypropylene ether glycol,polytetramethylene ether glycol, polyethylene ether glycol,l,2-polydimethylethylene ether glycol, polydecamethylene ether glycol,and so forth. Further examples 3 of polyalkylene ether glycols which canbe used according to this invention are described in Patent No.2,492,959.

Various organic diisocyanates can be used to react with the difunctionalhydroxy polymers to form the prepolymer. Aromatic, aliphatc, as well ascycloaliphatic diisocyanates or combinations thereof, can be used.Representative diisocyanates include 4-methyl-m-phenylene diisocyanate,m-phenylene diisocyanate, 4,4'-biphenylene diisocyanate, methylene bis(4-phenylisocyanate), 4-chloro-1,3-phenylene diisocyanate,1,5-naphthalene diisocyanate, 1,4-tetramethylene diisocyanate,1,6-hexamethylene diisocyanate, 1,10-decamethylene diisocyanate,1,4-cyclohexylene diisocyanate,4,4'-methylene-bis(cyclohexylisocyanate), and 1,5 tetrahydronapthalenediisocyanate. Arylene diisocyanates, i.e., those in which each of theisocyanate groups is attached directly to an aromatic ring arepreferred. In general, they react more rapidly than do the alkylenediisocyanates. The diisocyanates may contain other substituents,although those which are free from reactive groups other than the twoisocyanate groups are ordinarily preferred. In the case of the aromaticcompounds the isocyanate groups may be attached either to the same or todiiferent rings. Dimers of the monomeric diisocyanates anddi(isocyanatoaryl)-ureas, such as di( 3-isocyanate-4-methylpheny1) ureamay also be used.

The patents to Frankenburg No. 2,957,852, Windemuth No. 2,948,691 andthe Hill No. 2,929,800 further show how the prepolymers can be prepared,as well as the reactants used in their preparation according to thisinvention.

The prepolymer is advantageously reacted with a compound containing atleast 2 active hydrogens, such as a :liamine, in the presence of asolvent to form a solution containing the resultant elastomeric polymer.The amount of diamine used can advantageously be stoichiometricallyequivalent to the amount of prepolymer used, but even more or less thanthe amount can be used. Generally, it is advisable to use sufiicientdiamine so that the viscosity 3f the resulting elastromeric polymersolution will have 1 viscosity of at least 50 poises or, advantageously,a viscosity between about 100 to 500 poises.

In general, the amount of diamine that can be used form the elastomericpolymer solution can be varied :onsiderably depending on a number offactors such as he particular diamine used to react with the prepolymer,:he reactants used to form the prepolymer, the properties lesired to hepossessed by the end products and so forth. these and other factors willbe apparent to those skilled n the art and the exact amount of diaminethat can most rdvantageously be used to prepare the polymer can be'eadily determined by those skilled in the art by routine:xperimentation.

Various primary and secondary diarnines can be used 0 form theelastomeric polymers according to this invenion including aliphatic,allocyclic and inorganic diamines. lpecific examples of a number ofdiamines which can be rsed are hydrazine, ethylene diamine, piperazine,1,4dimino-2-methyl piperazine, 1,4-diamino-2,5-dimethyl pi- IeraZine,methylimino bis propylamine, etc. It should also e apparent to thoseskilled in the art that combinations f two or more diamines may be usedin the polymer. doreover, as already known in the art other compounds anbe used which have active hydrogen atoms present 11 at least two atomsof oxygen and/or nitrogen, i.e. mine, carboxyl or hydroxyl groups, asfully described in LS. Patent 2,917,489.

Various solvents can be used to form the elastomeric olymer solutions,as will be apparent to those skilled 1 the art, such as dimethylformamide, dimethyl sulfoxle, dimethyl acetamide, etc. Advantageously, aratio f 1:1 to 6:1 of the solvent to the polymer can be emloyed.

The coagulating bath, which is generally Water, into hich theelastomeric polymer solution is extruded, builds 9 its solvent contentduring the process due to extraction of the solvent from the elastomericpolymer solution. The extraction of the solvent initially takes placewhen the filaments are gathered together and pressure applied to thefilaments to consolidate them into a fused multifilament fiber. Thepressure can be applied by any suitable means known to those skilled inthe art such as pulling the filaments, under tension, down toward theapex of V-shaped grooves which have been cut in rollers, as shown in thedrawing, or by leading the filaments through any suitable restrictedarea so as to press the filaments together into the multifilament fiber.The solvent which builds up in the coagulating bath can be continuouslyremoved during the process to maintain, advantageously, the solventcontent at a desirable level, e.g. 40-60% solvent.

In the formation of filaments, the extrusion speeds 0btainable willdepend upon the bath temperature, the length of the bath, etc. Extrusionspeeds of 150 feet per minute and higher have been obtained using a bathapproximately 6 feet in length. The 150 feet per minute extrusion speedreferred to above is not limiting since higher extrusion speeds can beobtained. The temperature at which the chamber is maintained and thelength of time in which the filaments, or the multifilament fibers, areexposed to this temperature will vary depending upon the particularoperating conditions employed, the particular composition of theelastomeric polymer solution, and so forth. The most suitabletime-temperature relationship for each operation is a matter which canreadily be determined by one skilled in the art.

The invention can more readily be understood by referring to theaccompanying drawing which represents specific embodiments of theinvention but which is not intended in any way to limit the scope of theinvention.

in FIGURE 1, which is a top View of a spinning apparatus, an elastomericpolymer solution is extruded through a spinneret ll, into coagulatingbath 2, to form a plurality of filaments 3. These filaments are thenpassed over roll 4 and under roll 5 within the V-shaped grooves of eachroll, 6 and 7 respectively. Roll 5 is beneath roll 4 and parallelthereto. The V-shaped grooves gather the filaments together andconsolidate them into a fused multifilament fiber 8. As can readily beunderstood, the multifilament fiber will be more tightly fused when thefilaments are more firmly pressed toward the apex of the V-shapedgrooves as the fiber is under tension.

The multifilament fiber 8 is then passed over roll 9 and under roll it)within the V-shaped grooves of each roll, 11 and 12 respectively. Rolllltl is beneath roll 9 and parallel thereto. Rolls 9 and it arelaterally displaced with respect to rolls 4 and 5 so that when themultifilarnent fiber is drawn to the V-shaped grooves of rolls 9 and 10,it will tend to roll down the sides of the grooves, thus forming atwisted fiber 13. This twisting action on the fiber efiectssubstantially complete consolidation or fusion of the filaments of thefiber and impants a roundness thereto. The rolls 9 and 10 are laterallydisplaced at a distance that can be readily adjusted by routineexperimentation to determine the most suitable displacement distance. Alateral displacement which results in the multifilament fiber leavingroll 5 at an included angle of about (depending on the angle of thegroove 11) with respect to the axis of rotation of roll 5 may beemployed. The sides of the V-shaped grooves of course can be concave orconvex if desired and the angle of acuteness of the V-shape, as well asthe extent of the lateral displacement can readily be adjusted withrelation to each other to provide any suitable degree of twisting actiondesired.

FIGURE 2 shows a side View of FIGURE 1.

FIGURE 3 shows a more detailed View of roll 5 where the filaments havebeen gathered together to form the fused multifilament fiber 8.

FIGURE 4 shows a top view of a spinning apparatus wherein the rolls 9and 10, instead of being laterally displaced and parallel to rolls 4 and5, are placed at an angle with respect to rolls 4 and 5. This angle, asdetermined by the axis of the respective rolls, may be about 15(depending on the angle of groove 11) or any other suitable angle whichcan readily be determined by routine experimentation so that the fiberwill be subjected to a twisting action as it passes within the V-shapedgrooves 11 and 12 of rolls 9 and 10.

FIGURE shows a more detailed view of roll 9 where the fiber tends toroll down the side of V-shaped groove 11. As the fiber is withdrawn fromroll id it has become a twisted fiber 13.

FIGURE 6 is a cross-sectional view of the twisted multifilament fiber 13and shows that the fiber is rounded and that there are substantially fewinterstices between the individual filaments of the fiber.

These fibers are advantageously employed in making a material which willultimately have seams made in it. If the fiber is punctured with aneedle, for example, and relatively few filaments are broken, the fiberstill retains the characteristics and properties of the original fiberto a substantial degree.

The fibers prepared according to this invention possess many of theadvantages of both the mono-filament and multi-fdament fibers. Althoughthese fibers are strong,

there is little tendency for the individual filaments to separate awayfrom the fiber and get tang ed in the fiber guides of an apparatus usedin connection with the fibers.

I claim:

1. The method of wet spinning isocyanate modified dihydroxy elastomericpolymers dissolved in a solvent to produce a multifilament fiber havinga substantially round cross-section, which comprises extruding thepolymer solution through a plurality of orifices into a liquid coag-.

ulating bath to form a plurality of filaments, gathering together thefilaments and applying sufiicient pressure to them, while they are incontact with the coagulating bath liquid and while they are in the stateof semi-plastic flow, to consolidate them into a fused multifilamentfiber, and subsequently imparting a twisting action to the multifilamentfiber while it is in contact with the coagulating bath liquid and Whileit is in the state of semi-plastic flow.

2. The method of wet spinning isocyanate modified dihydroxy elastomericpolymers dissolved in a solvent to produce a multifilament fiber havinga substantially round cross-section, which comprises extruding thepolymer solution through a plurality of orifices into a liquidcoagulating bath to form a plurality of filaments, gathering togetherthe filaments and applying sufficient pressure to them, while they arein contact with the coagulating bath liquid and while they are in thestate of semi-plastic 6 flow, to consolidate them into a fusedmultifilament fiber, and subsequently imparting a twisting action to themultifilament fiber while it is in contact with the coagulating bathliquid and while it is in the state of semi-plastic flow, said twistingaction being accomplished by rolling the multfilament fiber over asmooth surface.

3. An apparatus for treating isocyanate modified dihydroxy filamentsformed by coagulating an isocyanate modified dihydroxy elastomericpolymer solution by extrusion into a fluid bath to form a plurality offilaments which comprises means for consolidating a plurality of saidfilaments into a fused multifilament fiber by imparting pressure to theplurality of filaments while they are still in the state of at leastsemi-plastic flow and in contact with the bath fluid, and means forimparting a twisting action to said fiber to effect substantiallycomplete consolidation of the filaments making up the fiber and toimpart a roundness theerto.

4. The apparatus according to claim 3 in which the means forconsolidating a plurality of the filaments into a multifilament is aroller provided with a plurality of V-shaped grooves about its peripherythrough which the plurality of filaments are led.

5. The apparatus according to claim 4 in which the means for imparting atwisting action to the multifilament fiber is a pair of rollerspositioned obliquely to the path of the fiber and containing l-shapedgrooves about their periphery, whereby the fiber is passed, within theV- shaped grooves, over one roller and under the other.

6. The apparatus according to claim 5 in which the means for imparting atwisting action to the multifilament fiber is a pair of rollerscontaining V-shaped grooves about their periphery, said V-shaped groovesbeing displaced laterally to the path of the fiber so that as the fiberis passed, through the V-shaped grooves, over one roll and under theother, there is provided a twisting action on the fiber.

7. The apparatus according to claim 4 in which the means for imparting atwisting action to said fibers comprises a V-shaped groove lying in aplane which is angularly displaced from a plane of which themultifilament fiber is an element.

References Eited in the file of this patent UNITED STATES PATENTS2,041,798 Taylor May 26, 1936 2,072,926 Taylor Mar. 9, 1937 2,079,133Taylor May 4, 1937 2,149,425 Draemann Mar. 7, 1939 2,786,737 Hawtin eta1 Mar. 26, 1957 2,804,645 Wilfong Sept. 3, 1957 2,923,598 Reis et al.Feb. 2, 1960

1. THE METHOD OF WET SPINNING ISOCYANATE MODIFIED DIHYDROXY ELASTOMERICPOLYMERS DISSOLVED IN A SOLVENT TO PRODUCE A MULTIFILAMENT FIBER HAVINGA SUBSTANTIALLY ROUND CROSS-SECTION, WHICH COMPRISES EXTRUDING THEPOLYMER SOLUTION THROUGH A PLURALITY OF ORIFICES INTO A LIQUIDCOAGULATING BATH TO FORM A PLURALITY OF FILAMENTS, GATHERING TOGETHERTHE FILAMENTS AND APPLYING SUFFICIENT PRESSURE TO THEM, WHILE THEY AREIN CONTACT WITH THE COAGULATING BATH LIQUID AND WHILE THEY ARE IN THESTATE OF SEMI-PLASTIC FLOW, TO CONSOLIDATE THEM INTO A FUSEDMULTIFILAMENT FIBER, AND SUBSEQUENTLY IMPARTING A TWISTING ACTION TO THEMULTIFILAMENT FIBER WHILE IT IS IN CONTACT WITH THE COAGULATING BATHLIQUID AND WHILE IT IS IN THE STATE OF SEMI-PLASTIC FLOW.